Electronic regulator



Patented Dec. 2, 1941 2,265,031 moraomc REGULATOR Donald W. Bxner, Forest Hills, PaL, assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 16, 1940, Serial No. 319,317

4 Claims.

My invention relates to a protective circuit for electrical apparatus that has application where two or more devices perform mutually related functions in a. system in such manner that failure of one device will cause serious disturbance to the operation of the system if the other devices continue to function normally.

If the several devices are designed and arranged to operate with the same value of alternating current supplied, they may all be connected in series with an alternating-current power source. If such devices are separately supplied from the secondary windings of their several associated transformers, and the primary windings of such transformers are connected in series to an alternating-current source, the loads on the several secondary windings will affect the distribution of the primary voltage across the several. primary windings. The respective primary windings will not divide the line voltage of the source equally unless the apparent power taken by the several secondary loads is equal. In accordance withmy invention, each transformer must be so designed as to operate on the full line voltage of the alternating-current source without excessive magnetic saturation and the consequent excessive exciting current which would accompany such high saturation.

If transformers so designed are connected with their primary windings in series and the load ate upon substantially full line voltage of the source without excessive saturation, so that upon failure of the load on one transformer it will develop a high reactance in series with the other transformers for greatly diminishing the voltage of a regulated generator would normally cause the generator to receive maximum field current.

erenc'e to the accompanying drawing, in which the single figure is a diagrammatic view of apparatus and circuits illustrating a preferred embodiment of the invention.

Referring to the drawing, an alternating-current generator I- is illustrated having an armature winding connected to supply current to a power circuit represented by conductors 2 and 3, and having a field winding 4 that is connected to be energized from grid-controlled, gas-filled, electronic tubes 5 and 6, which together form a full-Wave rectifier unit. The current output of the tubes 5 and 6 is controlled by a detector tube 1 and a full-wave rectifier tube 8 in a manner to be later explained. For the purpose of providing controlled power for the field winding 4, a transformer is provided having a primary winding II connected to the power circuit conductors 2 and 3 and secondary windings I2, I3 and I4. -The winding I2 serves as an anode transformer, and the opposite ends thereof are connected by conductors I5 and I6, respectively, to theanodes l1 and I8 of tubes 5 and 5. The tubes 5 and 6 are provided with cathodes I9 and 2| that are connected by conductors 22 and 23 to the filament transformer winding I3. The circuit for energizing the field winding 4 extends from the anode transformer winding I2 through conductors I5 and I5, tubes 5 and 5, conductors 22 and 23, filament transformer winding I3, conductor 24, field winding 4, and conductor 25 to the center point of the winding I2.

A phase-shifting network is connected to the transformer winding I4 and comprises a resistor 26 connected to one end of the winding I4 and a capacitor 21 connected to the opposite end of the winding H, the outer ends of which are joined at a junction point 28, from which a circuit ex-' tends through conductor 29, resistors 32 and 33, and conductor 34 to the midpoint of the winding I4. grids 35 and 35 that are connected, respectively,

through resistors 31 and 38 and conductors 33' and 42 to selected points along the resistors 32 and 33. The phase shifting network from the transformer winding I4 introduces an alternating voltage into the grid control circuits-of the' tubes 5 andv 6 through resistors 32 and 33, that is lagging in phase behind, the voltage applied to the anode circuit of the tubes. The grid control circuit of the tubes 5 and 5 extends from the cathodes I9 and 2| through conductors 22 and 23, transformer winding I3, conductor 43 to a variable contact member 44 having slida-ble en- My invention will be better understood by refgagement with a resistor 45, through the right The tubes 5 and 5 are provided with,

from transformers I] and 52, respectively, having primary windings 53 and 54 connected in series through a conductor 5| between line-circuit conductors 2 and 3. The transformer 52' is provided with a filament transformer winding 56 and with an anode transformer winding 51, the winding 58 being connected by conductors I! and 59 to the filament 82 of the tube 8, and

the outer ends of the winding 51 being connected by conductors 83 and 84 to anodes 65 and 66 of the tube 8. The tube 8 functions as a full-wave rectifier to supply unidirectional current which flows from thecathode 62 through conductors 58 and 59, winding 56, and from the center point of the winding through conductor 48, resistor 15,

conductor 81 to the center point of the winding 51, and to the anodes 85 and 68 of the tube 8. The tube 8 thus applies a substantially constant unidirectional potential across the resistor #5, a portion of which is introduced into the grid control circuit of the tubes 5 and 8. V

The transformer 5! is provided with a secondary winding 1!, the two outer ends of which are connected throughresistors 12 to the cathode 13 of the tube 1'. The tube 1 serves as a detector tube responsive to the voltage of the generator i, and controls the flow ofcurrent between the anode i4 and the cathode 13 through the resistor 41 in shunt relation to the resistor 65 upon varying conductivity of the tube l as caused by variations in its filament voltage. Thiscurrent flows between conductors so and 8'! v as supplied by the rectifier tube 3.

it will be noted that in the abbve-traced grid control circuit for the tubes and d, a positive component of voltage is added across the portion of the resistor 5 between points s4 and i5, and that 9; negative component is added across the resistor 4?. Since the. output voltage of the tube 8 remains substantially constant, the voltm age across the portion of the resistor t5 included in. the grid control circuit remains substantially constant. As the voltage between power circuit conductors 2 and 3 increases above the desired value, the temperature of the cathode [3 tube i increases rapidly, thus rapidly increasing the conductivity of the-tube and permitting a greater current to flow through the tube and through the resistor t? to increase the voltage drop across the resistor 63, and, therefore, to maize the grids so and 3d of the tubes 65 and s more negative, causing the output current from the tubes & and t to the field t to de crease. Similarly, a in the voltage between thev line circuit conductors 2 causes a decrease in the temperature of the cathode '53 and a corresponding decrease in cur rent flow through resistor ti, so that and 38 of the tubes 5 8 become more positive and efiect an increase in the current flow therethrough to the held E; to increase'the voltage output of the generator,

The-resistors 52' in circuit with the filament it of the tube are not essential, but may of that is sufliciently high that the reactive voltis desired to load the transformers II and 2 equally. Minor adjustments in the load ratio between the two transformers II and I! may be made by a load balancing resistor I1 connected in parallel relation to the resistor 45. I

If, during the operation of the electronic regulator above disclosed, the tube I should fail, by its filament burning out, or the circuit thereto should 'become interrupted, the load on the transformer 5i isdecreased to zero, and the prir'nary winding 53 becomes a high reactance device in series with the primary winding 54 of the transformer 52, so that both the anode voltage and the cathode voltage are decreased to a very low value. thus causing the voltage drops across resistors and 41 to become zero. As a result.

there is substantially no potential difference be-:

tweenthe points 44 and I! in the grid control circuit, and the current passed by the tubes 5 and 6 will then be wholly dependent upon thesetting of the phase-shifting circuit from the transformer winding ll, which causes the tubes 5 and 8 to become conductive at some particular I point of the anode circuit voltage wave. It will be noted that upon failure of the tube 1, which controls the voltage drop across resistor 41, for introducing a negative bias to the grids of the tubes 5 and 6, these grids would receive a maximumpositive potential causing the tubes I and 6 to deliver maximum field current to the 'generator unless the positivecomponent of grid control voltage across the resistor 45 were eliminated from the grid control circuit. Likewise,

should the circuit of tube 8 fail for any reason,

the potential between points 44 and I8 would dis- 7 appear or become substantially zero.

It will be'apparent to those skilled in the art that modifications in the circuits and apparatus illustrated and described may be made within the spirit of my invention, and I do not wish tobe limited otherwise than by the scope of the appended claims. r

I claim as my invention:

i. In an electronic regulator, in combination, a, control circuit, a pair of mutually related electronic elements for developing control potentials in said control circuit, a pair of electric transformers havingtheir secondary windings connected to supply current to said pair of mutually related electronic elements respectively, and having their primary windings connected in series to an alternating-current source, said transformers beingdesigned to normally operate at sufficiently low flux densities thatupon failure of of the 55 the secondary circuit of either transformer a reactance is developed in the primary circuit theretiais in said control circuit, a pair of electric transformershaving their secondary windings connected to supply current to said pair of mutually related electronic elements respectively, and

having their primarysvindings connected in series to an alternating=current source, said transformers being designed to operate at the full voitage of the alternating-currentscurce at a flux density sumciently low to develop a reactive drop thereacross in the primary circuit that is substcntlally the applied voitage of the circuit to to increase the load on transformer BE, it substantiolly reduce the-voltage across the p 1- mary winding of one of said transformers upon a failure in the secondary circuit of the other. 3. In an electronic regulator, in combination, a

I control circuit, means for introducing control podesigned to normally operate at sufliciently low flux densities that upon failure of the secondary circuit of either transformer a reactance is developed in the primary circuit thereof that is sufnciently high that the reactive voltage drop across the primary winding becomes substantially the voltage of the primary circuit.

4. In an electronic regulator, in combination,

a control circuit, means for introducing control potentials into said control circuit" comprising a local circuit network and two electronic devices mutually related for developing controlled potentials across portions of said network, one of said devices comprising a source of unidirectional current for the network and the other governing the current flow through a portion thereof, a pair of transformers having theirsecondary windings connected to supply. current respectively to said pair of electronic devices and having their primaries connected in series to an alternating-current source, said transformers being designed to normally operate at sufiiciently low flux densities that upon failure of the secondary circuit of either transformer a reactance is developed in the primary circuit thereof that is sufliciently high that the reactive voltage drop across the primary winding becomes substantially the volt age of the primary circuit.

DONALD W. EXNER. 

